Iran's navy claimed its warships entered the Mediterranean on Saturday to show its 'might' to regional countries, as a high-level American official was due to arrive in Israel.

The claim, released through the official Iranian news agency, came at a time of growing speculation that Israel will launch airstrikes against Iran's nuclear programme.

"The strategic navy of the Islamic Republic of Iran has passed through the Suez Canal for the second time since the (1979) Islamic Revolution," said navy commander Admiral Habibollah Sayari.

He did not say how many vessels had passed through the canal, or what missions they were planning to carry out in the Mediterranean, but said the flotilla had previously docked in the Saudi port city of Jeddah. Two Iranian ships, the destroyer Shahid Qandi and supply vessel Kharg, had docked in the Red Sea port on February 4, according to Iranian media. But Iran has made claims about its military moves before that have later proved wrong. There was speculation the ships may have been on the way to Syria, where Iran has supported President Bashar al-Assad's ruthless repression of an uprising.

The admiral said the deployment would also convey Tehran's "message of peace and friendship."

Two Iranian vessels reportedly passed through the Suez Canal last February, soon after Egypt's uprising, for the first time since the 1979 revolution.

Israel put its navy on alert following Saturday's announcement. Tensions are running high between the two enemies after a series of assassinations in Iran of nuclear scientists, and terrorist attacks against Israeli diplomats.

The announcement came as Foreign Secretary William Hague warned in Saturday's edition of The Daily Telegraph of the danger of a nuclear Cold War in the Middle East because of Iran'snuclear programme.

Iran's navy has been involved in sabre rattling several times in recent months, especially in the strategic Strait of Hormuz where it faces powerful American naval forces.

Later on Saturday US National Security Advisor Tom Donilon was due to arrive in Israel for talks with senior Israeli officials on a range of issues, including Iran and Syria, the White House announced.

The announcement came as US Secretary of State Hillary Clinton and European Union foreign policy chief Catherine Ashton voiced cautious optimism about the prospect for Iran to return to nuclear talks with six world powers.

The top White House aide's visit "is the latest in a series of regular, high-level consultations between the United States and Israel, consistent with our strong bilateral partnership, and part of our unshakable commitment to Israel's security," a White House statement said.

The visit comes ahead of a visit to Washington by Israeli Prime Minister Benjamin Netanyahu for White House talks with Obama in early March, where the leaders are likely to focus on Iran and the failure to find a deal on resuming direct talks between Israeli and Palestinian negotiators.

Meanwhile, during a press conference in Washington with Ashton, Mrs Clinton called a letter that the European Union's top diplomat had received from Iran "an important step" towards negotiations after a year-long hiatus.